Radon in homes and other dwellings

Radon in homes and other dwellings

Last updated: September 23, 2024
HealthLinkBC File Number: 42
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What is radon?

Radon is a colourless, odourless radioactive gas that is released from the breakdown of uranium that is naturally present in rock, soil and groundwater.

When released outdoors, radon gas becomes diluted with air and poses little risk. However, radon gas can build up inside homes and other buildings and pose a hazard to your health.

Radon primarily enters buildings through the soil underneath the building. It can move through cracks in the foundation, construction joints, as well as gaps around service pipes, floor drains and window casements.

How does radon affect my health and what is my risk?

Exposure to radon over the long-term can cause lung cancer. About 16% of lung cancer deaths in Canada are due to indoor radon exposure. Radon is the leading cause of lung cancer for non-smokers and the second leading cause among smokers. You have a one in 3 chance of developing lung cancer in your lifetime if you are exposed to high levels of radon and you smoke or used to smoke. For non-smokers, the risk is one in 20.

Because lung cancer takes time (years) to develop, the risk of developing lung cancer from radon depends on its concentration in the indoor air of the home or building and the length of time exposed. Since radon exposure does not produce immediate symptoms, the only way to know your exposure is to test your home for radon. Remediation should be conducted if levels are found above the recommended guideline below. Remediation is the process of reducing the amount of radon in homes and other buildings.

How is radon measured?

Radon in air is measured in becquerels per cubic meter (Bq/m3), a measure of radioactive decay per second. Indoors, radon can be measured using both long-term (3 months to a year) and short-term (2 to 7 days) tests.

Long-term testing is recommended to provide an accurate measurement of radon concentrations in a home or building. Long-term testing is easy to conduct and can be done using do-it-yourself radon test kits. These kits contain small wall-mounted radon detectors that are placed in the home for 3 months or longer, ideally during the fall or winter (6 to 12 months is recommended). Because radon levels can vary greatly over a period of 24 hours, short-term tests (2 to 7 days) are not recommended.

What are the guideline levels for radon?

The current Health Canada guideline for radon is 200 Bq/m3. If the average annual radon concentration of a dwelling exceeds 200 Bq/m3, then Health Canada recommends remediation. A dwelling includes homes and other places where people spend 4 or more hours. It’s recommended that higher concentrations be remediated sooner. For more information, please visit Health Canada: Radon www.canada.ca/en/health-canada/services/health-risks-safety/radiation/radon.html.

Is there radon in B.C.?

Yes, elevated levels of radon are found throughout most of the province, but some regions are known to have typically higher concentrations.

Sampling results from a recent Health Canada cross-country survey of radon concentrations found that the percentage of homes in the Northern and Interior health regions that reported radon levels greater than 200 Bq/m3 ranged from 6 to 30%. It’s still possible that homes in other parts of the province have high radon levels but more testing needs to be conducted and reported.

For more information on radon levels in B.C., visit https://bccdc.shinyapps.io/bcradonmap.

Should I get my home tested?

Everyone is encouraged to test their home for radon.

Radon levels vary widely from house to house, even in the same neighborhood. This is because concentrations in a building depend on several factors, including the geology of the area, housing construction and characteristics like air exchange in the home. In general, radon concentrations tend to be highest in the lowest levels of a building, such as basements.

The only way to be sure of the concentration of radon in your home is to test. Those living in Interior and Northern communities in B.C. are especially encouraged to test their homes for radon.

How do I get my home tested?

Radon testing is easy and can be done with do-it-yourself tests. The cost of a testing device and results is about $30 to $50.

A long-term radon detector is placed in the lowest level of your home that is occupied for more than 4 hours per day. Specific instructions are provided with the detector.

Once the test is completed (ideally over a period of 3 months to one year, including some winter months), the detector is mailed to a lab for analysis. The lab then provides the testing results, in the form of an average radon concentration over the test period. This level can then be compared to Health Canada’s guideline of 200 Bq/m3. Because no level of radon is considered to be without harm, individuals are encouraged to consider remediation, even if levels are close to or below the guideline.

Where can I get a radon testing device?

For a list of suppliers of radon testing devices, visit the BC Centre for Disease Control www.bccdc.ca/resource-gallery/Documents/Guidelines%20and%20Forms/Guidelines%20and%20Manuals/EH/RPS/Radon%20Testing%20in%20Cda.pdf (PDF 220 KB) or look under ‘home inspection services’ in your local phone listings.

Test kits are also available from:

You can also hire a certified radon measurement professional to come and test your home. Health Canada recognizes the Canadian National Radon Proficiency Program. For more information, please visit https://c-nrpp.ca.

What can I do if tests show my home has elevated radon levels?

There are several things you can do to reduce the levels of radon in your home:

  • Ventilate the basement sub-flooring by installing a small air pump to draw the radon from below the concrete slab and vent it outside before it enters the home or building
  • Improve ventilation or air flow (natural or forced) of crawl spaces, basements and other areas on the lower levels of the home or building by opening windows or using ceiling fans
  • Seal cracks and openings in basement floors and walls, and around pipes and drains

Certified radon mitigation professionals are available to provide advice and conduct remediation. To find a radon professional in your area, visit Canadian National Radon Proficiency Program (C-NRPP) at https://c-nrpp.ca or the Canadian Association of Radon Scientists and Technologists at www.carst.ca. After remediation is completed, another radon test should be done to ensure that levels have been reduced.

For more information

For more information, please contact your local health authority environmental health officer by visiting www2.gov.bc.ca/gov/content/health/about-bc-s-health-care-system/partners/health-authorities/regional-health-authorities.

For additional information, visit: